1. Field of Invention
The present invention relates to a package process and structure. More particularly, the present invention relates to a semiconductor packaging process and a structure having an improved processing reliability.
2. Description of Related Art
In this information age, electronic products have become indispensable tools in every part of our daily life. At the core of each electronic product is usually a silicon chip that connects with other chips or passive electrical devices through a substrate. Since the chip is firmly attached as well as electrically connected to the substrate through a packaging process, a number of packaging structures have been developed such as bump chip carrier (BCC) package, film package and quad flat no-lead (QFN) package. All these packages have superior electrical performance and heat dissipation capacity.
However, in a bump chip carrier (BCC) package, the carrier for supporting the chip package must be removed by etching in the final step. Since the carrier is made from copper, the etched away copper material may leak into the surroundings causing metallic contamination. In addition, if the etching solution is improperly mixed or the ingredients thereof are slightly out of proportion, either the carrier is incompletely removed or the metallic contact surface is over-removed.
In the fabrication of a film package, two reflow steps are required to connect a film with a substrate electrically. Solder balls are implanted on the film in the first reflow step, while the film is attached to the substrate through the solder balls in a second reflow step. Meanwhile, each reflow operation causes some warpage of the film. In addition, since the film is thin relative to the substrate, the warpage of the film is intensified.
In the fabrication of a quad flat no-lead (QFN) package, the leads thereof are attached to a carrier through a tape. Since the tape is made from a soft material, a press head of a wire-bonding machine, when pressing wires onto the leads, caves into the tape resulting in a shift of the leads. Therefore, the wire-bonding head can hardly target the leads with any accuracy. Ultimately, reliability of the connection between the conductive wire and the lead is compromised.